Method of recording an electronic image

ABSTRACT

A method of recording an electron image, in which a metal of high reflectivity is vacuum-evaporate on a substrate of glass, plastic, or the like, an electronic image is irradiated onto the organic film coated on the metal thereby to record the image by giving the reaction of polymerization, cross-linking, or degradation to said organic material to the extent corresponding to the irradiation intensity, and then the image is obtained which is quantitatively corresponding to the intensity distribution of the incident electrons by again vacuumevaporating a metal of high reflectivity on the recorded image. Further, a method of recording an electronic image, in which the sensitivity of a recording plate is improved by using a preexposure method, whereby a recordable exposure range is increased thereby to control the lightness and color of the image.

[22] Filed:

United States Patentn91 Kanaya et al I [54'] METHOD or RECORDING AN ELECTRONIC IMAGE [75] Inventors: Koichi Kanaya; Hisazo Kawakatsu;

Nobufumi Atoda, all of Tokyo, Japan [73'] Assignee: Kogyo Giiutsuin Ministry of International Trade and Industry, Japanese Government, Tokyo-to,- Japan Nov. 4, 1970 [21] Appl. No.: 86,830

[30] Foreign Application Priority Data Nov.-f6, 1969 Japan ....44/ss4os Nov. 6, 1969 Japan .44/88409 [52] US. Cl. ..34li/1, 346/135, 340/173 LM [51] Int. Cl. ..G0ld 15/34 5s FieldofSearch .;346/l,77 12,135;

[56] References Cited UNITED STATES PATENTS 3,144,331 8/19 64 Thomm'es ..96/l15PX n 11 3,727,233 [451 Apr. 10, 1973 3,286,025 11/1966 lngersoll ..l78/6.6R

Primary Examiner--Joseph W. Hartary Attorney-Robert E. Burns and Emmanuel J. Lobato ABSTRACT A method of recording an electron image, in which a metal of high reflectivity is vacuum-evaporate on a substrate of glass, plastic, or the like, an electronic image is irradiated onto the organic film coated on the metal thereby to record the image by giving the reaction of polymerization, cross-linking, or degradation to said organic material to the extent corresponding to the irradiation intensity, and then the image is obtained which is quantitatively corresponding to the intensity distribution of the incident electrons by again vacuum-evaporating a metal of high reflectivity on the recorded image. Further, a method of recording an electronic image, in which the sensitivity of a recording plateis improved by using a pre-exposure method, whereby a recordable exposure range is increased thereby to control the lightness and color of the image. I

8 Claims, 5 Drawing Figures PATENTED 1 01973 3, 727, 233

SHEET 1 BF 3 FIG. HA)

FIG.

out BOJ M; zmwmo u m3 m n hi h METHOD OF RECORDING AN ELECTRONIC IMAGE BACKGROUND OF THE INVENTION recording the image on a recording plate employing a film of organic material as a recording medium thereof by utilizing a pre-exposure method.

Heretofore, a photographic dry plate of silver halogenide series has been used for recording an electronic image produced by an electron microscope and various types of electron beam apparatuses. With this dry plate the image is recorded by converting the intensity distribution of an electron beam transmitted through an object into the photographic density distribution on the plate by means of chemical treatment, and therefore the intensity distribution and the density distribution are varied depending upon the conditions of development treatment, whereby the analysis of the thickness or internal structure of an object to be inspected is made inaccurate. In addition, it is required for the measurement to employ the technique of optical measurementutilizing a photometer, and the like.

Further, as the silver halide emulsion are so large in graininess that. the magnification of optical enlargement is limited, and therefore it is necessary to considerably increase the magnifying degree of the electron microscope in order to obtain a photograph of large magnification. Therefore, the current density -irradiating onto the object becomes too high, resulting in undesirable phenomena such as change, drift and contamination of theobject. Furthermore, as the usable irradiation quantity range is so narrow that it becomes difficult to record an image whose electron beam intensity is-so widely ranged as found in, for instance, an electron diffraction image, and therefore it becomes impossible to record an image of high contrast. In order to correct these defects, it has been proposed to utilize a phenomena in which a contamination comprising a compoundof hydrocarbon is stuck on a surface being irradiated with an electron beam, but the contamina- '.tion-sticking speed is so slow as impractical in use for the method of recording an image produced by the electron microscope.

On the other hand, a recording plate of organic material adapted to record an electronic image by applying a nature that the reaction of polymerization, cross-linking, or degradation is caused by irradiating an electron beam onto a certain kind of organic material, has some specific features superior to that of a dry plate employing a normal silver halogenide emulsion. In other words,'the superior specific features are that it is very great in contrast and fine in resolution, and it is easy to know quantitatively the thickness or the internal structure of an electron microscope specimen and the intensitydistribution of an electron beam because the relationships between the irradiation quantity of an incident electrons and the color or the photographic density observed in a recorded image due to the optical interferences are constant irrespective of a development treatment. It is predicted to use such a record plate of organic material in place of a conventional dry and the use thereof provides a useful means for the measurement of the diameter and intensity distribution of an electron beam produced by various types of electron beam apparatuses which has had many defects to be solved. However, there are still many points to be improved in order to suficiently utilize the abovedescribed specific features. First of all, these organic materials are, in general, low in the sensitivity to an electron beam in comparison with an emulsion of silver halogenide series, and therefore are not sufficient for recording the high magnification image of the electron microscope. secondarily, the reaction of polymerization, cross-linking, or degradation is not caused at a quantity of irradiation below a certain value thereof, and so the effectively usable irradiation quantity range is limited. In other words, a portion whose electron current intensity is lower than a certain value in one electronic image is not recorded, and therefore it is impossible to record with fidelity an image whose intensity ranges widely, an electron diffraction image or an intensity distribution of an electron beam.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of recording an electronic image on a recording plate which is simple in construction, easy in handling, high in contrast and fine in resolution.

Another object of the present invention is to realize a color image with high cleamess.

Still another object of the present invention is to provide a method of recording an electronic image in which a dark room is not required thanks of the utilization of not photo-sensitive organic material, the development treatment can be accomplished without a special skill and further the handling is simple.

An further object of the present invention is to provide a method of recording an electronic image by utilizing pre-exposure technique, in which byirradiating an electron beam or a light beam evenly or uniformly onto a recording plate the sensitivity of the recording plate 'is improved, the recordable exposure range is spreaded, and the lightness and color of the recorded image can be controlled.

The nature, principles, and utility of the invention will be more clearly apparent. from the following detailed description, in which reference is made to the accompanying drawings, in which like parts are designated by like reference numerals.

BRIEF DESCRIPTION OF THE DRAWING In the drawings:

FIGS. 1(A), 1(3), and 1(C) are sections of recording plates provided for explaining the principle of this invention; I

FIG. 2 is an optical characteristic diagram of a recording plate when pre-exposure is not applied thereto; and

FIG. 3 is also an optical characteristic diagram of a recording plate when the thereto.

DETAILED DESCRIPTION OF THE INVENTION Withreferencenow to the drawing and more particularly to FIG. 1 thereof, there is illustrated a record pre-exposure is applied ing plate, indicating the recording of an image by an electron beam and its after-treatment. FIG. 1(A) shows a condition in which a metal 2 of high optical reflectivity is vacuum-evaporated on a cleaned substrate 1 of glass or plastic and then is evenly or uniformly coated with polymeric organic material 3 from approximately 1,000 A to several-tens p. in thickness. Under these conditions, when an electron beam 4 running through an object to be inspected is irradiated to the organic material 3, the reaction of polymerization, cross-linking, or degradation takes place in corresponding to the irradiation intensity depending upon the sort of organic material. FIG. 1(B) indicates the recording plate, shown in FIG. 1(A), which is rinsed in a proper solvent as a development treatment. The polymerization or cross-linking layer with a film thickness corresponding to the irradiation of the electron beam remains on the plate, or the degradation layer is dissolved away thereby to attain an organic material layer which has a three-dimensional structure as shown by numeral 5 in the figure. Thus, an electronic image is recorded by converting the distribution of irradiation intensity into the distribution of the film thicknessv of organic material. FIG. 1(C) shows the treatment of the plate, in which a' metal 6 of high reflectivity is again vacuumevaporated on the organic material layer.

The image recorded as the film thickness of organic material shows an interference color image corresponding to the film thickness in case that a lightsource is of a white light, and s howsa shaded image in case that the light-source is of almono-color, due to the interference phenomenon of light within the organic material layer. The term shaded image is herein used to'designate an image defined by contrasting bright and hereinafter), the sensitivity thereof is increased, and

, further a color to be observed is'properly varied by the quantity of pre-exposure. It is one of the specific features of the present invention that the sensitivity and color thus can be controlled by the technique of pre-exposure.

Next, in the method of recording an electronic image, a method of improving the sensitivity of a recording plate by using the preexposure treatment thereby to widen the exposure range in which the recording is possible, is explained hereinafter.

When electrons are irradiated on the organic recording plate, the reaction of, polymerization, cross-linking or degradation is carried out to an extent correspondent to the irradiation quantity; when the recording plate is rinsed in a proper solvent, the polymerization and cross-linking layers correspondent to the irradiation' quantity remain on the plate, or the degradation layer is dissolved away. Thus, the image is recorded by converting the distribution of irradiation intensity into the film thickness distribution. The recorded image shows an interference color corresponding tothe film thickness oforganic material in case of observing with dark portionsof different photographic densities. The V vacuum-evaporated metal film layers 2 and 6 areto in.-

' crease the reflectivity of both upper and lower surfaces of the organic material thereby to increasethe purity of the interference color. When it is required to observe the image by utilizing a reflecting light, the film of the metal -2 is thickened so that itsreflectivity'be approximately Land the film thickness of the metal6 is adjustedsoas to obtain the proper purity and lightness of interference color. On the other hand, when a transmission light 8 is to be observed, both metals 2 and 6 are made approximately the samein thickness and semitransparent thereby to obtain the proper purity of color and lightness of the-transmission light.

One embodiment of the recording plate experimentally obtained is described as follows:

In observing a'transmission light; when a transparent glass plate of60- X 55 X 1 mm is employed for the substrate Land aluminum for metalsZand 6, both of which are approximately 300 A in thickness, the color purity and lightness of thetransmission light becomes proper for observation. When a dimethylpolysiloxane film containing vinyl radicals of approximately 1 p. thicknessisemployed for an organic material 3, at an accelerating voltageof 'K\ the sensitivity thereof to an electron is almost as much as that of a commercial dry plate of high resolution and the graininess are not distinguished upto the optical englargement of twohundred-fold. In addition, if electron-irradiation is evenly or uniformly applied to the plate before recording an image '(this will be called pre-exposure a white light, and a shaded image in case of observing with a mono-color light. As one embodiment, FIG. 2 exhibits the photographic density observed by using a mono-color light of its wave length 5,46lA calculated frornthe cross-linking characteristic of the dimethylpolysiloxane film containing vinyl radials of 1.] u in -thicknessat the accelerating voltage of 50 KV and the optical interference theory. The axis of abscissa is for an' irradiation quantity expressed by a logarithmic scale, while the axis of ordinate is for a photographic density. The colors observed by using a white light also can be calculated in the same way, and the representative ones thereof are added on the upper part of FIG. 2. When the irradiation quantity is less than the value of Qm in FIG. 2, across-linking layer is not left, and therefore the portion of animage correspondingto the irradiation quantity is not recorded, and further it will be seen that the sensitivity is lower than that of a normal photographic plate. In order to overcome such defect, the following method is applied: v

First, the recording plate is evenly or uniformly irradiated by an electron beam which may be substituted by a light in thecase that a photo-sensitive organic materialis used, and then the recording is carried out by irradiating an electronic image to be recorded (this will be called image-exposure hereinafter). Thepreexposure may be carried out after the image-exposure. The cross-linking (or polymerization, or degradation) reaction is carried out upto an extent corresponding to an irradiation quantity Qp in the pre-exposed organic materiaLand this effect semipermanently remains therein. Therefore, assuming that the irradiation quantity required to obtain a color or a photographic density is 0 when the pro-exposure is not carried out, the

image-exposure quantity required for obtaining the same photographic density or'color is sufficient with FIG. 3. As apparent from FIG. 3, the sensitivity is higher than that of FIG. 2; and there is no lower limitation of recordable irradiation quantity which is correspondent to Qm. In addition, the pre-exposure quantity Qp is varied depending on the range of the intensity of an electron image to be recorded and on purposes of recording. For instance, in case that an image whose electron current intensity ranges from the maximum value to zero is to be recorded;'when the pre-exposure Qp is adapted to be equal to Qm, the zero point of the electron current is coincident with the building-up of the photographic density. Further, in case that a portion where no electron beam is irradiated is required to ference theory, the colorimetric theory, and the reaction of polymerization,cross-linking, and degradation of an organic material, and therefore the purity, hue, and lightness of a color observed in a recorded image can be accurately calculated on the basis of the optical theory. Therefore, an irradiation intensity distribution can be directly obtained from the observed color without using a photo-meter as found in a conventional method, and further it becomes easier to give a quantitative analysis to the thickness of an object to be inspected and to the internal structure thereof. In other words, as a large difference between irradiation intensities is recorded by the difference of colors and a small difference therebetween by the difference of lightness, thereby to easily recognize these differences.

' Secondarily; the graininess of organic material is, in

general, so small in comparison with an emulsion of silver ha'logenide series that a record of high resolution can be accomplished, whereby a photograph of high magnification can be attained by optical enlargement after recording the image under conditions where the electron current irradiated through the object is not so dense to cause the change, drift, and contamination of the object, that is, at a low magnification.

Thirdly, the thickness of organic material being polymerized, cross-linked, or degraded with respect to a same irradiation quantity becomes greater according to the thickness of initially coated organic material. Therefore, in comparison with that of 'anorma] photov graphic plate extremely high contrast can be realized by making heavy the thickness of organic material'to be coated. This is advantageous for recording images of pre-exposure treatment is not applied thereto, but the whole range of the electron current intensity from the maximum to zero is made to be recorded by applying the pre-exposure treatment. This is advantageous for measuring the intensity distribution or the diameter of the electron beam and for recording such an image with a very high contrast as the electron diffraction image.

Sixthly; by applying the pre-exposure technique the irradiation quantity required for recording an image becomes smaller than that required in case that the preexposure is not applied, that is to say, the sensitivity is increased. This is a useful nature to a case wherein a high magnification image produced by an electron microscope is recorded by using the recording plate of organic material.

While the principles of the invention have been described as above in connection with specific embodiment, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.

We claim:

1. A method of color recording an electronic image which comprises vacuum-evaporating a first metal layer on a transparent plastic or glass plate, coating on said first metal layer a film of organic material having a thickness from 1,000A to several-tens microns, irradiating said electronic image on said film to record said image on said film by polymerizing, cross-linking or degrading said organic material to an extent corresponding at each image point to the intensity of said irradiation, developing said film by treatment with organic solvents to produce a three dimensional image defined by variation in the thickness of said film corresponding quantitatively at each image point to variation in irradiation intensity by said electronic image, and vacuum evaporating a second metal layer of a thickness to be semitransparent on said developed film to obtain by optical interference within said developed film a color image in which the color at" respective image points varies corresponding to the intensity distribution of the irradiating electronic image.

2. A method of recording an electronic image as claimed in claim 1, in which said first metal layer is thicker than said second metal layer.

3. A method of recording an electronic image as claimed in claim 1, in which said first and second metal layers are made approximately the same in thickness and are semitransparent.

4. A method of recording an electronic image as claimed in claim 1, further comprising the step of additionally uniformly irradiating said film with electrons prior to the developing of said film to increase the sensitivity and exposure range of said film and improve the color tone or photographic density of the recorded image.

5. A method of recording an electronic image as claimed in claim 4, in which said uniform irradiation is effected as a preoperational step prior to exposure of said filmto said electronic image.

6. A method of recording an electronic image as claimed in claim 4, in which said uniform irradiation is effected as a postoperationalstep after exposure of said film to said electronic image.

3,727,233 r 7 -7. A method of recording an electronic image as claimed in claim 1, in which said first and second metal layers areof aluminum with a thickness of approximately 300 A. y 8. A method of recording an electronic image as claimed in claim 1, in which said organic material film is a dimethylpolysiloxane film containing vinyl radicals and having a thickness of approximately 1 [.L. 

2. A method of recording an electronic image as claimed in claim 1, in which said first metal layer is thicker than said second metal layer.
 3. A method of recording an electronic image as claimed in claim 1, in which said first and second metal layers are made approximately the same in thickness and are semitransparent.
 4. A method of recording an electronic image as claimed in claim 1, further comprising the step of additionally uniformly irradiating said film with electrons prior to the developing of said film to increase the sensitivity and exposure range of said film and improve the color tone or photographic density of the recorded image.
 5. A method of recording an electronic image as claimed in claim 4, in which said uniform irradiation is effected as a preoperational step prior to exposure of said film to said electronic image.
 6. A method of recording an electronic image as claimed in claim 4, in which said uniform irradiation is effected as a postoperational step after exposure of said film to said electronic image.
 7. A method of recording an electronic image as claimed in claim 1, in which said first and second metal layers are of aluminum with a thickness of approximately 300 A.
 8. A method of recording an electronic image as claimed in claim 1, in which said organic material film is a dimethylpolysiloxane film containing vinyl radicals and having a thickness of approximately 1 Mu . 